The brilliant @Foone@twitter.com recently tweeted "One of the biggest problems with the English language is that we don't really have a good gender neutral version of sir/ma'am, and retail workers are required addresses customers with that kind of honorific".
That made me think, could "their" be used as a gender-neutral ma'am/sir honorific? Adoption may be assisted by the "there" homophone; if you're working retail and say "hello, their," or "may I help you, their?" to those out of the loop it just sounds like you're being polite in US-Midwestern.
Nonbinary and non-gender-conforming folks out there, what do you think of all this? What honorifics, if any, do you appreciate used in your direction?